With rapid development of a packet service and an intelligent terminal, a service of a high speed and a large data volume imposes an increasing demand for a spectrum. According to a newly issued FCC international spectrum white paper, unlicensed spectrum resources are more than licensed spectrum resources. Therefore, data transmission by using an unlicensed spectrum resource becomes a development trend.
An unlicensed spectrum includes frequency bands used for industrial, scientific and medical (Industrial, scientific and medical, ISM) devices and the like. In the prior art, a main technology used in an ISM frequency band is Wireless Fidelity (Wireless Fidelity, WiFi), a wireless local area network (wireless local network, WLAN), Bluetooth, ZigBee, or the like. For WiFi, quality of service (quality of service, QoS) is poor, efficiency in aspects such as multi-user scheduling is low, and a mobility management function is limited. Therefore, a Long Term Evolution (Long Term Evolution, LTE) system in the 3rd Generation Partnership Project (the 3rd Generation Partnership Project, 3GPP) is applied to an unlicensed spectrum, so that unlicensed spectrum resources can be more efficiently utilized and available spectrum bandwidth of an LTE user can be expanded.
An unlicensed spectrum is shared by many users, and the users may belong to different radio access technologies (radio access technology, RAT), such as LTE, WiFi, and Bluetooth. In LTE, WiFi, Bluetooth, and the like, it needs to detect whether the unlicensed spectrum is occupied by another device. Therefore, before performing transmission, an LTE, a WiFi, or a Bluetooth device or the like that uses the unlicensed spectrum needs to listen to whether the spectrum is idle, that is, needs to support “listen before talk (Listen before Talk, LBT)”, so as to avoid interfering with another user who is using the unlicensed spectrum. Moreover, a maximum occupation time for a user that obtains the unlicensed spectrum is also correspondingly specified. The user needs to release the unlicensed spectrum after using for a specific time and starts to contend for the unlicensed spectrum again after waiting for a specific time. Therefore, each user is given a fair opportunity to contend for and use the unlicensed spectrum. When a channel is about to become idle or is idle, each device may perform reservation so as to determine which device can use an idle unlicensed spectrum. However, in the prior art, LTE does not support LBT or channel reservation; consequently, an LTE system cannot legally or properly share an unlicensed spectrum with another device or another system. Therefore, enabling LTE to support LBT, reserve a channel, and schedule UE on the reserved channel becomes a problem in urgent need of resolving.